I have a b16a1 in my 91 civic si and I might sound like a fool but i always thought the vtec kicked in at 4200 in it but i found out today is supposed to engage at 5500-5700 rpm, now heres the problem I have put different known working ecu in my car and it still engages at 4200 rpm, cleaned pressure switch and screen, checked oil, everything. Also I unplugged the oil pressure swicth and ran the same and threw codes so im think something is wrong there i believe, Please someone that knows what it might be let me know I'm out of ideas thanks

EDIT: I MEANT TO SAY AFTER UNPLUGGING THE PRESSURE SWITCH MY CAR THREW NO CODES SORRY